Dynamic evolved packet gateway selection

ABSTRACT

In aspects of the disclosure, a method, an apparatus, and a computer program product for wireless communication are provided. In one aspect, the apparatus determines if a connection to a PLMN has been established. In another aspect, the apparatus builds a FQDN based on the determination by attempting to build the FQDN using each of the prioritized FQDNs in order of priority until the FQDN is built, building the FQDN using a PLMN ID of the PLMN if it is determined that the PLMN is found in the list, or building the FQDN based on the wildcard PLMN if it is determined that the list comprises the wildcard PLMN. Further still, the apparatus selects an ePDG based on the FQDN.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of U.S. Provisional Application Ser.No. 62/160,572, entitled “DYNAMIC EVOLVED PACKET DATA GATEWAY (ePDG)SELECTION” and filed on May 12, 2015, which is expressly incorporated byreference herein in its entirety.

BACKGROUND

Field

The present disclosure relates generally to communication systems, andmore particularly, to dynamic evolved packet data gateway (ePDG)selection.

Background

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. Typical wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources (e.g., bandwidth,transmit power). Examples of such multiple-access technologies includecode division multiple access (CDMA) systems, time division multipleaccess (TDMA) systems, frequency division multiple access (FDMA)systems, orthogonal frequency division multiple access (OFDMA) systems,single-carrier frequency division multiple access (SC-FDMA) systems, andtime division synchronous code division multiple access (TD-SCDMA)systems.

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. An example telecommunication standardis Long Term Evolution (LTE). LTE is a set of enhancements to theUniversal Mobile Telecommunications System (UMTS) mobile standardpromulgated by Third Generation Partnership Project (3GPP). LTE isdesigned to better support mobile broadband Internet access by improvingspectral efficiency, lowering costs, improving services, making use ofnew spectrum, and better integrating with other open standards usingOFDMA on the downlink (DL), SC-FDMA on the uplink (UL), andmultiple-input multiple-output (MIMO) antenna technology. However, asthe demand for mobile broadband access continues to increase, thereexists a need for further improvements in LTE technology. Preferably,these improvements should be applicable to other multi-accesstechnologies and the telecommunication standards that employ thesetechnologies.

SUMMARY

In aspects of the disclosure, a method, an apparatus, and a computerprogram product for wireless communication are provided. In one aspect,the apparatus connects to a wireless communication network. In anotheraspect, the apparatus obtains an internet protocol (IP) address from thewireless communication network; determine if a connection to a firstpublic land mobile network (PLMN) has been established. In a furtheraspect, the apparatus builds a fully qualified domain name (FQDN) basedon the determination. In still a further aspect, the apparatus selectsan ePDG based on the FQDN. For example, a list of PLMN-specific FQDNsmay include a prioritized list of FQDNs each associated with a specificPLMN. In yet another aspect, when it is determined that the connectionto the first PLMN has been established, the apparatus may build the FQDNby retrieving the list of PLMN-specific FQDNs, determining if the firstPLMN is found in the list of PLMN-specific FQDNs, and attempting tobuild the FQDN using each of the prioritized FQDNs in order of priorityuntil the FQDN is built, or retrieving a list comprising a plurality ofvisited PLMNs (VPLMNs) when the first PLMN is a VPLMN, determining ifthe first PLMN is found in the list comprising the VPLMNs, and buildingthe FQDN using a PLMN identification (PLMN ID) of the first PLMN if itis determined that the first PLMN is found in the list comprising theVPLMNs. In yet a further aspect, when it is determined that theconnection to the first PLMN has not been established, the apparatusbuilds the FQDN by retrieving the list of PLMN-specific FQDNs,determining if the list of PLMN-specific FQDNs comprises a wildcardPLMN, and building the FQDN based on the wildcard PLMN if it isdetermined that the list of PLMN-specific FQDNs comprises the wildcardPLMN.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a network architecture.

FIG. 2 is a diagram illustrating an example of an access network.

FIG. 3 is a diagram illustrating an example of a DL frame structure inLTE.

FIG. 4 is a diagram illustrating an example of an UL frame structure inLTE.

FIG. 5 is a diagram illustrating an example of a radio protocolarchitecture for the user and control planes.

FIG. 6 is a diagram illustrating an example of an evolved Node B anduser equipment in an access network.

FIG. 7A is a diagram illustrating an example of a roaming architecturefor an evolved packet system in which a packet data network (PDN)gateway is located in a home public land mobile network (HPLMN).

FIG. 7B is a diagram illustrating an example of a roaming architecturefor an evolved packet system in which a packet data network (PDN)gateway is located in a visited public land mobile network (VPLMN).

FIG. 8 is a flowchart of a method of wireless communication.

FIG. 9 is a conceptual data flow diagram illustrating the data flowbetween different means/components in an exemplary apparatus.

FIG. 10 is a diagram illustrating an example of a hardwareimplementation for an apparatus employing a processing system.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented withreference to various apparatus and methods. These apparatus and methodswill be described in the following detailed description and illustratedin the accompanying drawings by various blocks, modules, components,circuits, steps, processes, algorithms, etc. (collectively referred toas “elements”). These elements may be implemented using electronichardware, computer software, or any combination thereof. Whether suchelements are implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem.

By way of example, an element, or any portion of an element, or anycombination of elements may be implemented with a “processing system”that includes one or more processors. Examples of processors includemicroprocessors, microcontrollers, digital signal processors (DSPs),field programmable gate arrays (FPGAs), programmable logic devices(PLDs), state machines, gated logic, discrete hardware circuits, andother suitable hardware configured to perform the various functionalitydescribed throughout this disclosure. One or more processors in theprocessing system may execute software. Software shall be construedbroadly to mean instructions, instruction sets, code, code segments,program code, programs, subprograms, software modules, applications,software applications, software packages, routines, subroutines,objects, executables, threads of execution, procedures, functions, etc.,whether referred to as software, firmware, middleware, microcode,hardware description language, or otherwise.

Accordingly, in one or more exemplary embodiments, the functionsdescribed may be implemented in hardware, software, firmware, or anycombination thereof. If implemented in software, the functions may bestored on or encoded as one or more instructions or code on acomputer-readable medium. Computer-readable media includes computerstorage media. Storage media may be any available media that can beaccessed by a computer. By way of example, and not limitation, suchcomputer-readable media can comprise a random-access memory (RAM), aread-only memory (ROM), an electrically erasable programmable ROM(EEPROM), compact disk ROM (CD-ROM) or other optical disk storage,magnetic disk storage or other magnetic storage devices, combinations ofthe aforementioned types of computer-readable media, or any other mediumthat can be used to store computer executable code in the form ofinstructions or data structures that can be accessed by a computer.

FIG. 1 is a diagram illustrating an LTE network architecture 100. TheLTE network architecture 100 may be referred to as an Evolved PacketSystem (EPS) 100. The EPS 100 may include one or more user equipment(UE) 102, an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN)104, an Evolved Packet Core (EPC) 110, and an Operator's InternetProtocol (IP) Services 122. The EPS can interconnect with other accessnetworks, but for simplicity those entities/interfaces are not shown. Asshown, the EPS provides packet-switched services, however, as thoseskilled in the art will readily appreciate, the various conceptspresented throughout this disclosure may be extended to networksproviding circuit-switched services.

The E-UTRAN includes the evolved Node B (eNB) 106 and other eNBs 108,and may include a Multicast Coordination Entity (MCE) 128. The eNB 106provides user and control planes protocol terminations toward the UE102. The eNB 106 may be connected to the other eNBs 108 via a backhaul(e.g., an X2 interface). The MCE 128 allocates time/frequency radioresources for evolved Multimedia Broadcast Multicast Service (MBMS)(eMBMS), and determines the radio configuration (e.g., a modulation andcoding scheme (MCS)) for the eMBMS. The MCE 128 may be a separate entityor part of the eNB 106. The eNB 106 may also be referred to as a basestation, a Node B, an access point, a base transceiver station, a radiobase station, a radio transceiver, a transceiver function, a basicservice set (BSS), an extended service set (ESS), or some other suitableterminology. The eNB 106 provides an access point to the EPC 110 for aUE 102. Examples of UEs 102 include a cellular phone, a smart phone, asession initiation protocol (SIP) phone, a laptop, a personal digitalassistant (PDA), a satellite radio, a global positioning system, amultimedia device, a video device, a digital audio player (e.g., MP3player), a camera, a game console, a tablet, or any other similarfunctioning device. The UE 102 may also be referred to by those skilledin the art as a mobile station, a subscriber station, a mobile unit, asubscriber unit, a wireless unit, a remote unit, a mobile device, awireless device, a wireless communications device, a remote device, amobile subscriber station, an access terminal, a mobile terminal, awireless terminal, a remote terminal, a handset, a user agent, a mobileclient, a client, or some other suitable terminology.

The eNB 106 is connected to the EPC 110. The EPC 110 may include aMobility Management Entity (MME) 112, a Home Subscriber Server (HSS)120, other MMES 114, a Serving Gateway 116, a Multimedia BroadcastMulticast Service (MBMS) Gateway 124, a Broadcast Multicast ServiceCenter (BM-SC) 126, and a Packet Data Network (PDN) Gateway 118. The MME112 is the control node that processes the signaling between the UE 102and the EPC 110. Generally, the MME 112 provides bearer and connectionmanagement. All user IP packets are transferred through the ServingGateway 116, which itself is connected to the PDN Gateway 118. The PDNGateway 118 provides UE IP address allocation as well as otherfunctions. The PDN Gateway 118 and the BM-SC 126 are connected to the IPServices 122. The IP Services 122 may include the Internet, an intranet,an IP Multimedia Subsystem (IMS), a PS Streaming Service (PSS), and/orother IP services. The BM-SC 126 may provide functions for MBMS userservice provisioning and delivery. The BM-SC 126 may serve as an entrypoint for content provider MBMS transmission, may be used to authorizeand initiate MBMS Bearer Services within a PLMN, and may be used toschedule and deliver MBMS transmissions. The MBMS Gateway 124 may beused to distribute MBMS traffic to the eNBs (e.g., 106, 108) belongingto a Multicast Broadcast Single Frequency Network (MBSFN) areabroadcasting a particular service, and may be responsible for sessionmanagement (start/stop) and for collecting eMBMS related charginginformation.

FIG. 2 is a diagram illustrating an example of an access network 200 inan LTE network architecture. In this example, the access network 200 isdivided into a number of cellular regions (cells) 202. One or more lowerpower class eNBs 208 may have cellular regions 210 that overlap with oneor more of the cells 202. The lower power class eNB 208 may be a femtocell (e.g., home eNB (HeNB)), pico cell, micro cell, or remote radiohead (RRH). The macro eNBs 204 are each assigned to a respective cell202 and are configured to provide an access point to the EPC 110 for allthe UEs 206 in the cells 202. There is no centralized controller in thisexample of an access network 200, but a centralized controller may beused in alternative configurations. The eNBs 204 are responsible for allradio related functions including radio bearer control, admissioncontrol, mobility control, scheduling, security, and connectivity to theserving gateway 116. An eNB may support one or multiple (e.g., three)cells (also referred to as a sectors). The term “cell” can refer to thesmallest coverage area of an eNB and/or an eNB subsystem serving aparticular coverage area. Further, the terms “eNB,” “base station,” and“cell” may be used interchangeably herein.

The modulation and multiple access scheme employed by the access network200 may vary depending on the particular telecommunications standardbeing deployed. In LTE applications, OFDM is used on the DL and SC-FDMAis used on the UL to support both frequency division duplex (FDD) andtime division duplex (TDD). As those skilled in the art will readilyappreciate from the detailed description to follow, the various conceptspresented herein are well suited for LTE applications. However, theseconcepts may be readily extended to other telecommunication standardsemploying other modulation and multiple access techniques. By way ofexample, these concepts may be extended to Evolution-Data Optimized(EV-DO) or Ultra Mobile Broadband (UMB). EV-DO and UMB are air interfacestandards promulgated by the 3rd Generation Partnership Project 2(3GPP2) as part of the CDMA2000 family of standards and employs CDMA toprovide broadband Internet access to mobile stations. These concepts mayalso be extended to Universal Terrestrial Radio Access (UTRA) employingWideband-CDMA (W-CDMA) and other variants of CDMA, such as TD-SCDMA;Global System for Mobile Communications (GSM) employing TDMA; andEvolved UTRA (E-UTRA), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE802.20, and Flash-OFDM employing OFDMA. UTRA, E-UTRA, UMTS, LTE and GSMare described in documents from the 3GPP organization. CDMA2000 and UMBare described in documents from the 3GPP2 organization. The actualwireless communication standard and the multiple access technologyemployed will depend on the specific application and the overall designconstraints imposed on the system.

The eNBs 204 may have multiple antennas supporting MIMO technology. Theuse of MIMO technology enables the eNBs 204 to exploit the spatialdomain to support spatial multiplexing, beamforming, and transmitdiversity. Spatial multiplexing may be used to transmit differentstreams of data simultaneously on the same frequency. The data streamsmay be transmitted to a single UE 206 to increase the data rate or tomultiple UEs 206 to increase the overall system capacity. This isachieved by spatially precoding each data stream (i.e., applying ascaling of an amplitude and a phase) and then transmitting eachspatially precoded stream through multiple transmit antennas on the DL.The spatially precoded data streams arrive at the UE(s) 206 withdifferent spatial signatures, which enables each of the UE(s) 206 torecover the one or more data streams destined for that UE 206. On theUL, each UE 206 transmits a spatially precoded data stream, whichenables the eNB 204 to identify the source of each spatially precodeddata stream.

Spatial multiplexing is generally used when channel conditions are good.When channel conditions are less favorable, beamforming may be used tofocus the transmission energy in one or more directions. This may beachieved by spatially precoding the data for transmission throughmultiple antennas. To achieve good coverage at the edges of the cell, asingle stream beamforming transmission may be used in combination withtransmit diversity.

In the detailed description that follows, various aspects of an accessnetwork will be described with reference to a MIMO system supportingOFDM on the DL. OFDM is a spread-spectrum technique that modulates dataover a number of subcarriers within an OFDM symbol. The subcarriers arespaced apart at precise frequencies. The spacing provides“orthogonality” that enables a receiver to recover the data from thesubcarriers. In the time domain, a guard interval (e.g., cyclic prefix)may be added to each OFDM symbol to combat inter-OFDM-symbolinterference. The UL may use SC-FDMA in the form of a DFT-spread OFDMsignal to compensate for high peak-to-average power ratio (PAPR).

FIG. 3 is a diagram 300 illustrating an example of a DL frame structurein LTE. A frame (10 ms) may be divided into 10 equally sized subframes.Each subframe may include two consecutive time slots. A resource gridmay be used to represent two time slots, each time slot including aresource block. The resource grid is divided into multiple resourceelements. In LTE, for a normal cyclic prefix, a resource block contains12 consecutive subcarriers in the frequency domain and 7 consecutiveOFDM symbols in the time domain, for a total of 84 resource elements.For an extended cyclic prefix, a resource block contains 12 consecutivesubcarriers in the frequency domain and 6 consecutive OFDM symbols inthe time domain, for a total of 72 resource elements. Some of theresource elements, indicated as R 302, 304, include DL reference signals(DL-RS). The DL-RS include Cell-specific RS (CRS) (also sometimes calledcommon RS) 302 and UE-specific RS (UE-RS) 304. UE-RS 304 are transmittedon the resource blocks upon which the corresponding physical DL sharedchannel (PDSCH) is mapped. The number of bits carried by each resourceelement depends on the modulation scheme. Thus, the more resource blocksthat a UE receives and the higher the modulation scheme, the higher thedata rate for the UE.

FIG. 4 is a diagram 400 illustrating an example of an UL frame structurein LTE. The available resource blocks for the UL may be partitioned intoa data section and a control section. The control section may be formedat the two edges of the system bandwidth and may have a configurablesize. The resource blocks in the control section may be assigned to UEsfor transmission of control information. The data section may includeall resource blocks not included in the control section. The UL framestructure results in the data section including contiguous subcarriers,which may allow a single UE to be assigned all of the contiguoussubcarriers in the data section.

A UE may be assigned resource blocks 410 a, 410 b in the control sectionto transmit control information to an eNB. The UE may also be assignedresource blocks 420 a, 420 b in the data section to transmit data to theeNB. The UE may transmit control information in a physical UL controlchannel (PUCCH) on the assigned resource blocks in the control section.The UE may transmit data or both data and control information in aphysical UL shared channel (PUSCH) on the assigned resource blocks inthe data section. A UL transmission may span both slots of a subframeand may hop across frequency.

A set of resource blocks may be used to perform initial system accessand achieve UL synchronization in a physical random access channel(PRACH) 430. The PRACH 430 carries a random sequence and cannot carryany UL data/signaling. Each random access preamble occupies a bandwidthcorresponding to six consecutive resource blocks. The starting frequencyis specified by the network. That is, the transmission of the randomaccess preamble is restricted to certain time and frequency resources.There is no frequency hopping for the PRACH. The PRACH attempt iscarried in a single subframe (1 ms) or in a sequence of few contiguoussubframes and a UE can make a single PRACH attempt per frame (10 ms).

FIG. 5 is a diagram 500 illustrating an example of a radio protocolarchitecture for the user and control planes in LTE. The radio protocolarchitecture for the UE and the eNB is shown with three layers: Layer 1,Layer 2, and Layer 3. Layer 1 (L1 layer) is the lowest layer andimplements various physical layer signal processing functions. The L1layer will be referred to herein as the physical layer 506. Layer 2 (L2layer) 508 is above the physical layer 506 and is responsible for thelink between the UE and eNB over the physical layer 506.

In the user plane, the L2 layer 508 includes a media access control(MAC) sublayer 510, a radio link control (RLC) sublayer 512, and apacket data convergence protocol (PDCP) 514 sublayer, which areterminated at the eNB on the network side. Although not shown, the UEmay have several upper layers above the L2 layer 508 including a networklayer (e.g., IP layer) that is terminated at the PDN gateway 118 on thenetwork side, and an application layer that is terminated at the otherend of the connection (e.g., far end UE, server, etc.).

The PDCP sublayer 514 provides multiplexing between different radiobearers and logical channels. The PDCP sublayer 514 also provides headercompression for upper layer data packets to reduce radio transmissionoverhead, security by ciphering the data packets, and handover supportfor UEs between eNBs. The RLC sublayer 512 provides segmentation andreassembly of upper layer data packets, retransmission of lost datapackets, and reordering of data packets to compensate for out-of-orderreception due to hybrid automatic repeat request (HARQ). The MACsublayer 510 provides multiplexing between logical and transportchannels. The MAC sublayer 510 is also responsible for allocating thevarious radio resources (e.g., resource blocks) in one cell among theUEs. The MAC sublayer 510 is also responsible for HARQ operations.

In the control plane, the radio protocol architecture for the UE and eNBis substantially the same for the physical layer 506 and the L2 layer508 with the exception that there is no header compression function forthe control plane. The control plane also includes a radio resourcecontrol (RRC) sublayer 516 in Layer 3 (L3 layer). The RRC sublayer 516is responsible for obtaining radio resources (e.g., radio bearers) andfor configuring the lower layers using RRC signaling between the eNB andthe UE.

FIG. 6 is a block diagram of an eNB 610 in communication with a UE 650in an access network. In the DL, upper layer packets from the corenetwork are provided to a controller/processor 675. Thecontroller/processor 675 implements the functionality of the L2 layer.In the DL, the controller/processor 675 provides header compression,ciphering, packet segmentation and reordering, multiplexing betweenlogical and transport channels, and radio resource allocations to the UE650 based on various priority metrics. The controller/processor 675 isalso responsible for HARQ operations, retransmission of lost packets,and signaling to the UE 650.

The transmit (TX) processor 616 implements various signal processingfunctions for the L1 layer (i.e., physical layer). The signal processingfunctions include coding and interleaving to facilitate forward errorcorrection (FEC) at the UE 650 and mapping to signal constellationsbased on various modulation schemes (e.g., binary phase-shift keying(BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying(M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded andmodulated symbols are then split into parallel streams. Each stream isthen mapped to an OFDM subcarrier, multiplexed with a reference signal(e.g., pilot) in the time and/or frequency domain, and then combinedtogether using an Inverse Fast Fourier Transform (IFFT) to produce aphysical channel carrying a time domain OFDM symbol stream. The OFDMstream is spatially precoded to produce multiple spatial streams.Channel estimates from a channel estimator 674 may be used to determinethe coding and modulation scheme, as well as for spatial processing. Thechannel estimate may be derived from a reference signal and/or channelcondition feedback transmitted by the UE 650. Each spatial stream maythen be provided to a different antenna 620 via a separate transmitter618TX. Each transmitter 618TX may modulate an RF carrier with arespective spatial stream for transmission.

At the UE 650, each receiver 654RX receives a signal through itsrespective antenna 652. Each receiver 654RX recovers informationmodulated onto an RF carrier and provides the information to the receive(RX) processor 656. The RX processor 656 implements various signalprocessing functions of the L1 layer. The RX processor 656 may performspatial processing on the information to recover any spatial streamsdestined for the UE 650. If multiple spatial streams are destined forthe UE 650, they may be combined by the RX processor 656 into a singleOFDM symbol stream. The RX processor 656 then converts the OFDM symbolstream from the time-domain to the frequency domain using a Fast FourierTransform (FFT). The frequency domain signal comprises a separate OFDMsymbol stream for each subcarrier of the OFDM signal. The symbols oneach subcarrier, and the reference signal, are recovered and demodulatedby determining the most likely signal constellation points transmittedby the eNB 610. These soft decisions may be based on channel estimatescomputed by the channel estimator 658. The soft decisions are thendecoded and deinterleaved to recover the data and control signals thatwere originally transmitted by the eNB 610 on the physical channel. Thedata and control signals are then provided to the controller/processor659.

The controller/processor 659 implements the L2 layer. Thecontroller/processor can be associated with a memory 660 that storesprogram codes and data. The memory 660 may be referred to as acomputer-readable medium. In the UL, the controller/processor 659provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover upper layer packets from the core network. The upper layerpackets are then provided to a data sink 662, which represents all theprotocol layers above the L2 layer. Various control signals may also beprovided to the data sink 662 for L3 processing. Thecontroller/processor 659 is also responsible for error detection usingan acknowledgement (ACK) and/or negative acknowledgement (NACK) protocolto support HARQ operations.

In the UL, a data source 667 is used to provide upper layer packets tothe controller/processor 659. The data source 667 represents allprotocol layers above the L2 layer. Similar to the functionalitydescribed in connection with the DL transmission by the eNB 610, thecontroller/processor 659 implements the L2 layer for the user plane andthe control plane by providing header compression, ciphering, packetsegmentation and reordering, and multiplexing between logical andtransport channels based on radio resource allocations by the eNB 610.The controller/processor 659 is also responsible for HARQ operations,retransmission of lost packets, and signaling to the eNB 610.

Channel estimates derived by a channel estimator 658 from a referencesignal or feedback transmitted by the eNB 610 may be used by the TXprocessor 668 to select the appropriate coding and modulation schemes,and to facilitate spatial processing. The spatial streams generated bythe TX processor 668 may be provided to different antenna 652 viaseparate transmitters 654TX. Each transmitter 654TX may modulate an RFcarrier with a respective spatial stream for transmission.

The UL transmission is processed at the eNB 610 in a manner similar tothat described in connection with the receiver function at the UE 650.Each receiver 618RX receives a signal through its respective antenna620. Each receiver 618RX recovers information modulated onto an RFcarrier and provides the information to a RX processor 670. The RXprocessor 670 may implement the L1 layer.

The controller/processor 675 implements the L2 layer. Thecontroller/processor 675 can be associated with a memory 676 that storesprogram codes and data. The memory 676 may be referred to as acomputer-readable medium. In the UL, the controller/processor 675provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover upper layer packets from the UE 650. Upper layer packets fromthe controller/processor 675 may be provided to the core network. Thecontroller/processor 675 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

FIG. 7A illustrates roaming architecture for an evolved packet system(EPS) 700 using various interfaces (e.g., S8, S2a, S2b, Gxa, Swn, SWa,STa, SWm, Gxb, S9, S6b, SWx, Rx, Gx, SWd, Gxc, SGi) in which a PDNgateway 724 is located in the home public land mobile network (HPLMN)706. FIG. 7B illustrates roaming architecture for an EPS 700 usingvarious interfaces (e.g., S5, S2a, S2b, Gxa, SWn, SWa, STA, Gxc, Gx,Gxb, SWm, SGi, Rx, SWd, SWx) in which the PDN gateway 724 is located ina visited public land mobile network (VPLMN) 702.

In an aspect, the ePDG 712 be located in the VPLMN 704 and may functionas a security gateway to provide network security and internet workingcontrol via an IPSec tunnel establishment based on information obtainedfrom the 3GPP AAA (Authentication, Authorization, and Accounting) Proxy714 via the SWm interface. For example, the ePDG 712 may enable cellularoperators to extend wireless coverage, reduce the load on the cellularnetwork, and make use of existing backhaul infrastructure to reduce thecost of carrying cellular calls.

The VPLMN 704 may also include a Serving Gateway 718 that routes andforwards data packets from UEs and act as the mobility anchor duringinter-eNB handovers. The Serving Gateway 718 may receive signals from anMME that controls the data traffic. Each UE that enters the EPS 700 maybe associated with a Serving Gateway. In addition, the VPLMN 704 mayalso include a visited Policy and Charging Rules Function (vPCRF) 716that may determine policy rules in the VPLMN 704. The vPCRF 716 mayoperate in the network core, access subscriber databases and chargingsystems, and make policy decisions for UEs in the VPLMN 704.

The HPLMN 706 may include, for example, a Home Subscriber Server (HSS)726 that acts as the master user database to support the IMS (IPMultimedia Subsystem) of the Operator's IP Services 730. For example,the HSS 726 may contain subscriber profiles, perform subscriberauthentication and authorization, and provide information about thesubscriber's location and IP information. In addition, the HPLMN 706 mayinclude a 3GPP AAA Server 722 that provides UE authentication via theEAP-AKA (Extensible Authentication Protocol—Authentication and KeyAgreement) authentication method. Furthermore, the HPLMN 706 may includea home Policy and Charging Rules Function (hPCRF) 728 that may determinepolicy rules in the HPLMN 706. The hPCRF 716 may operate in the networkcore, access subscriber databases and charging systems, and make policydecisions for UEs in the HPLMN 706.

Referring to FIGS. 7A and 7B, when a UE is powered on and if Non-3GPP IPAccess Networks 702 are available, the UE may decide, eitherautomatically by the UE or by policies such as the access networkdiscovery and selection function (ANDSF), to connect to one of theNon-3GPP IP Access Points 708, 710. The Non-3GPP IP Access Points may bea trusted access point 708 or an untrusted access point 710. Forexample, a trusted Non-3GPP IP Access point 708 can be a Wifi accesspoint that is deployed by a cellular communications operator (e.g.,AT&T, Verizon, Sprint, etc.) that allows a UE to connect to the cellularnetwork. Untrusted Non-3GPP IP Access point 710 can be a Wifi accesspoint that is deployed by an entity other the cellular communicationsoperator (e.g., WLAN, local coffee shop, airport, etc.) that allows a UEto connect to the cellular network. When the UE establishes a connectionto the untrusted Non-3GPP IP Access point 710, a local IP address can bereceived by the UE from the access network. The UE may select the ePDG712 by static configuration or dynamically using the local IP address.

In an aspect, if a selected ePDG 712 is not reachable from an untrustednon-3GPP access point 710, the UE may repeat the ePDG selection andselect a different ePDG if available. In addition, if the ePDG 712 needsto be dynamically selected when the UE roams in the VPLMN 704 where aVPLMN ID is known by the UE, the UE can construct a fully qualifieddomain name (FQDN) using the VPLMN ID as the Operator Identifier andemploy the domain name system (DNS) server function to obtain the IPaddress(es) of the ePDG(s) in the VPLMN. The UE can select an ePDGaddress from the list returned in the DNS response and initiate theinternet protocol security (IPsec) tunnel establishment. A UE connectedto one or multiple PDN Gateways may use a single ePDG. In case ofhandover between ePDGs, the UE may be temporarily connected to twoePDGs.

Additionally and/or alternatively, if the ePDG needs to be dynamicallyselected the UE can constructs a FQDN using a HPLMN identification(HPLMN ID) and employs the DNS server function to obtain the IPaddress(es) of the ePDG(s). The UE can select an ePDG address from thelist returned in the DNS response and initiates the IPsec tunnelestablishment. A UE connected to one or multiple packet data networkgateways (PDN GWs) 724 can use a single ePDG 712.

The ePDG FQDN may contain an operator identifier that uniquelyidentifies the PLMN where the ePDG is located. For example, the ePDGFQDN can be composed of seven labels. The last three labels can be“pub.3gppnetwork.org”. The third and fourth labels together can uniquelyidentify the PLMN. The first two labels shall be “epdg.epc”. The resultof the ePDG FQDN will be:

-   -   “epdg.epc.mnc<MNC>.mcc<MCC>.pub.3gppnetwork.org”

In the roaming case, the UE may utilize the services of the VPLMN. Inthis case, the ePDG FQDN Operator Identifier can be constructed asdescribed above, but using the mobile network code (MNC) and mobilecountry code (MCC) of the VPLMN.

In order to guarantee inter-PLMN DNS translation, the <MNC> and <MCC>coding used in the “epdg.epc.mnc<MNC>.mcc<MCC>.pub.3gppnetwork.org”format of the ePDG FQDN Operator Identifier can be <MNC>=3 digits and<MCC>=3 digits.

If there are only 2 significant digits in the MNC, one “0” digit shallbe inserted at the left side to fill the 3 digits coding of MNC in theePDG FQDN.

As an example, the ePDG FQDN Operator Identifier for MCC 345 and MNC 12is coded in the DNS as “epdg.epc.mnc012.mcc345.pub.3gppnetwork.org”.

However, ePDG selection procedures may not define what staticconfiguration is and how it is managed. Moreover, ePDG selectionprocedures may not address the following scenarios in both the staticand dynamic ePDG selection.

For example, cellular network operators may require a specific procedurefor selection of the ePDG 712 for S2b connectivity. At present, ePDGstatic selection and dynamic selection may be based on using the PLMNID. The current static and dynamic ePDG selection procedures may notsupport selection procedures where the UE selects an ePDG based on a setof FQDN(s) selected by the HPLMN 706, independently of the PLMN in whichthe UE is located. In addition, the current static and dynamic ePDGselection procedures may not support selection procedures where the UEselects an ePDG 712 based on the HPLMN ID, independently of the PLMN inwhich the UE is located. Further, the current static and dynamic ePDGselection procedures may not support selection procedures where the UEselects an ePDG based on a specific set of PLMN-specific FQDN(s) incertain PLMNs and uses the VPLMN ID in other PLMNs. Furthermore, thecurrent static and dynamic ePDG selection procedures may not supportselection procedures where the HPLMN 706 is allowed to indicate to theUE in which VPLMN 704 the UE is allowed to select an ePDG 712 (e.g., inorder to cater with transitory deployment phases where ePDGs aredeployed only by a subset of the roaming partners). The current staticand dynamic ePDG selection procedures may not support a selectionscenario where the UE is not attached to any PLMN and therefore has notsufficient information to create an FQDN based on the VPLMN ID. Stillfurther, the current static and dynamic ePDG selection procedures maynot support scenarios in which the ePDG must be selected in the VPLMN inorder to enable legal interception, depending on the local requirements.

Thus, there is a need to allow the UE to select an ePDG based on a setof information configured by the HPLMN, and based on the UE's knowledgeof the PLMN it is attached to. For example, there is a need to enablethe UE to select, independently of the VPLMN 704 in which the UE islocated, an ePDG (not illustrated in FIGS. 7A and 7B) in the HPLMN 706.In addition, there is a need to provide the UE with FQDNs that do notconform to the specified format of the ePDG FQDN (e.g., not based on thespecified format including the PLMN ID). Further, there is need toenable a UE to select an ePDG in the HPLMN 706 (e.g., based on thestandardized ePDG FQDN) when the UE is in the HPLMN 706 or is in aspecific set of VPLMNs 704.

Still further, there is a need to allow the UE to select an ePDG in theHPLMN or the VPLMN based on preconfigured PLMN-specific ePDG FQDNs whenthe UE is in the HPLMN or a set of VPLMNs (e.g., one of the VPLMNs inthe set), whereas for other VPLMNs the UE may select the VPLMN based onthe standardized format of the FQDN. In some scenarios, e.g. when the UEis not attached to a cellular access point (e.g., eNB), the UE may notbe aware of the PLMN or even the country in which the UE is located.Thus, there is a need to allow the UE to create an FQDN with the PLMN IDof the HPLMN.

Thus, in accordance with an aspect of the present disclosure, the UE maybe configured with a prioritized list of PLMN-specific FQDNs, which mayinclude a wildcard PLMN that is applicable to the case where the UE isnot attached to any PLMN. For example, the list of PLMN-specific FQDNsmay include an ePDG identifiers configuration with the FQDNs or IPaddresses of ePDGs in one or more PLMNs (e.g., this may include theHPLMN and VPLMNs). In an aspect, an entry in the ePDG identifiersconfiguration may include an “any PLMN” value for the PLMN, whichmatches any PLMN the UE is attached to. If the configuration informationcontains both an entry with the “any PLMN” value and an entry with thePLMN identity of the PLMN the UE is attached to, the UE may giveprecedence to the latter. For each PLMN, the list may contain one ormore PLMN-specific FQDNs in any format decided by the HPLMN 706 (i.e.,may be compliant to the standardized FQDN format or defined by theoperator). For example, the home operator can configure the UE to alwaysselect an ePDG in the HPLMN by associating the specific FQDN or IPaddress corresponding to the HPLMN with the “any PLMN” in the list ofPLMN-specific FQDNs. The FQDN corresponding to the wildcard PLMN can beused when the UE cannot determine which PLMN the UE is in, e.g., whenthe UE is not attached to any PLMN either via a cellular access point orany other access point.

In an aspect, the UE may also be configured with a list of VPLMNs forwhich selection of an ePDG 712 in the VPLMN 706 is preferred. Forexample, if a VPLMN is in such list, the UE may still be allowed toselect an ePDG in the HPLMN should the discovery and selection of anePDG in the VPLMN fail.

In a further aspect, the configuration of the UE can be based, forexample, on pre-configuration or based on ANDSF. In this way, the UE canbe provided with a configuration file containing such lists (e.g., oneor both lists) or extending the ANDSF managed object to contain suchlists.

In still a further aspect, VPLMNs for which ePDG selection in the VPLMNis allowed or preferred may include the VPLMNs for which ePDG selectionin the VPLMN is preferred or mandatory (e.g. due to legal interceptionrequirements). For example, the UE may be configured (e.g., by the homeoperator) to select an ePDG based on FQDN in the HPLMN by providingneither the ePDG identifiers configuration nor the ePDG selectioninformation. In other words, if the UE is in a given VPLMN, the ePDG inthe VPLMN can be selected to satisfy the VPLMN regulations. For example,the list can contain such VPLMN to enable the UE to discover and selectan ePDG in such VPLMN. Additionally and/or alternatively, the homeoperator can configure the UE to always attempt first to select an ePDGin the VPLMN by either not providing the ePDG identifiers configurationor by providing the ePDG identifiers only for the HPLMN, and/or byproviding the ePDG selection information containing the “any PLMN” valuefor the PLMN and the indication of “preferred”.

In an aspect, the UE can perform the ePDG selection according to thefollowing algorithm:

If the UE is attached via 3GPP to one of the PLMNs for which the UE hasbeen provided a PLMN-specific FQDN or the IP address for the PLMN in theePDG identifiers, then the UE shall use the corresponding FQDN from thelist of PLMN-specific FQDNs to obtain the IP address(es) of the ePDG(s)in the PLMN, or the UE shall use the corresponding configured IPaddress; and

If the UE is attached via 3GPP access to a VPLMN and the VPLMN is in alist of VPLMNs configured by the HPLMN (e.g. via pre-configuration orANDSF) as preferred for ePDG selection, the UE shall select the ePDG ofthe VPLMN by building the FQDN using the PLMN ID, if the UE is notattached to any PLMN, and the UE has been configured with an FQDNassociated to a wildcard PLMN (e.g., UE has been configured with an FQDNor IP address associated to a “any PLMN” value for the PLMN identity inthe ePDG identifiers configuration), then the UE shall use such FQDN(e.g., to obtain the IP address(es) of the ePDGs in the PLMN or thecorresponding configured IP address), in all other cases, the UE shallselect the ePDG of the HPLMN by building the FQDN using the PLMN ID.

In an aspect, the home operator can configure the UE to select an ePDGin the HPLMN corresponding to a specific FQDN by associating thespecific FQDN corresponding to the HPLMN with the wildcard PLMN in thelist of PLMN-specific FQDNs, by providing only such entry in the list ofPLMN-specific FQDNs, and by not providing the list of VPLMNs for whichselection of an ePDG in the VPLMN is allowed.

In an aspect, the home operator can configure the UE to select an ePDGin the HPLMN and build the FQDN for such ePDG with the PLMN ID byproviding neither the list of PLMN-specific FQDNs nor the list of VPLMNsfor which selection of an ePDG in the VPLMN is allowed. For example, thehome operator can configure the UE to select an ePDG based on FQDN inthe HPLMN by providing neither the ePDG identifiers configuration northe ePDG selection information.

Various solutions of the present disclosure describe a method in which aUE performs ePDG selection based on a series of information by using theFQDN of the ePDG for ePDG discovery.

In an aspect, the set of information may include the current PLMN inwhich the UE is attached or is located. In such case, the UE can createan FQDN with the PLMN ID of the HPLMN.

In a further aspect, the set of information may include a prioritizedlist of PLMN-specific FQDNs and the information on the current PLMN inwhich the UE is attached to or is located. In such case, if the currentPLMN is in the list, the UE can retrieve the corresponding FQDN(s) andattempt to build the FQDN with the first one PLMN ID in the list, thenthe second PLMN ID in the list, etc. Otherwise the UE can build the FQDNwith the PLMN ID of the HPLMN.

In a further aspect, the set of information may include a prioritizedlist of PLMN-specific FQDNs. Here, the UE may not know the current PLMNin which it is located. In such case, if the list contains a wildcardPLMN, the UE can use the FQDN corresponding to the wildcard PLMN tobuild the FQDN. Otherwise the UE may build the FQDN with the PLMN ID ofthe HPLMN.

Moreover, the set of information may include a list of VPLMNs for whichselection of an ePDG in the VPLMN is preferred and the information onthe current PLMN in which the UE is attached or is located. In suchcase, if the current PLMN is in the list, the UE can build the FQDN withthe PLMN ID of the current PLMN. Otherwise, the UE can build the FQDNwith the PLMN ID of the HPLMN.

Additionally, the set of information may include a list of VPLMNs forwhich selection of an ePDG in the VPLMN is preferred and the UE does notknow the current PLMN. In such case, the UE can create an FQDN with thePLMN ID of the HPLMN.

FIG. 8 is a flowchart 800 of a method of wireless communication. Themethod may be performed by a UE (e.g., UE 102).

In block 802, the UE can connect to a wireless communication network.For example, the UE can connect to the wireless communication networkusing an untrusted Non-3GPP IP access point.

In block 804, the UE can obtain an IP address from the wirelesscommunication network.

In block 806, the UE can determine if a connection to a public landmobile network (PLMN) through cellular network has been established. Forexample, the UE may determine that a connection to a cellular networkhas been established and may know the PLMN in which the UE is located.Alternatively, the UE may determine that no connection to a cellularnetwork has been established, and thus will not know the PLMN in whichthe UE is located.

In block 808, the UE can build a fully qualified domain name (FQDN)based on the determination.

In an aspect, when the UE determines that the connection to the PLMN hasbeen established, the UE can build the FQDN using a PLMN ID of a HPLMN.

In an aspect, when the UE determines that the connection to the PLMN hasbeen established, the UE can build the FQDN by retrieving a list ofPLMN-specific FQDNs, wherein the list comprises a prioritized list ofFQDNs associated with a specific PLMN, determining if the current PLMNis found in the list, and attempting to build the FQDN using each of theprioritized FQDNs in order of priority until the FQDN is built.

In an aspect, if the attempting to build the FQDN using the each of theprioritized FQDNs fails, the UE can build the FQDN using a PLMN ID of ahome PLMN (HPLMN).

In an aspect, when the UE determines that the connection to the PLMN hasnot been established, the UE can build the FQDN by retrieving a list ofPLMN-specific FQDNs, wherein the list comprises a prioritized list ofFQDNs associated with a specific PLMN, determining if the list comprisesa wildcard PLMN, and building the FQDN based on the wildcard PLMN if itis determined that the list comprises the wildcard PLMN. In an aspect,when the UE determines that the list does not comprise the wildcardPLMN, the UE can build the FQDN using a PLMN ID of a HPLMN. Optionally,the UE can include its location information that it is aware of in theDNS query message to the network. For example, by including the locationinformation to the DNS query sent to the network, the network (e.g., DNSserver), upon receiving the DNS request with the FQDN constructed usingthe HPLMN ID along with the UE location information may assign a localePDG that is close to the UE location. This may allow the UE to use alocal ePDG while the UE is roaming to a foreign country but is notattached to any cellular network.

In an aspect, when the UE determines that the connection to the PLMN hasbeen established, the UE can build the FQDN by retrieving a listcomprising information related to a VPLMNs, determining if the PLMN isfound in the list, and building the FQDN using a PLMN ID of the PLMN ifit is determined that the PLMN is found in the list. In an aspect, whenthe UE determines that the PLMN is not found in the list, the UE canbuild the FQDN using a PLMN ID of a HPLMN.

In an aspect, when the UE determines that the connection to the PLMN hasnot been established, the UE can build the FQDN using a PLMN ID of aHPLMN. Optionally, the UE can include its location information that itis aware of in the DNS query message to the network.

At step 810, the UE can select an ePDG based on the FQDN.

FIG. 9 is a conceptual data flow diagram 900 illustrating the data flowbetween different means/components in an exemplary apparatus 902. Theapparatus may be a UE. The apparatus includes a reception component 904that receives information from access point 950 (e.g., an access pointto a wireless communications network), a connection component 906, anobtaining component 908, a transmission component 910 that transmitsinformation to the access point 950, a determination component 912, anFDQN building component, and an ePDG selection component.

In an aspect, the connection component 906 can to connect to a wirelesscommunication network. For example, the UE can connect to the wirelesscommunication network using an untrusted Non-3GPP IP access.

In another aspect, the obtaining component 908 can obtain an IP addressfrom the wireless communication network.

In a further aspect, the determination component 912 can determine if aconnection to a PLMN has been established. For example, the UE maydetermine that a connection to a cellular network has been establishedand may know the PLMN in which the UE is located. Alternatively, the UEmay determine that no connection to a cellular network has beenestablished, and thus will not know the PLMN in which the UE is located.

In another aspect, the FDQN building component 914 can build a FQDNbased on the determination. For example, when the determinationcomponent 912 determines that the connection to the PLMN has beenestablished a signal can be sent to the FDQN building component 914, andthe FDQN building component 914 can build the FQDN using a PLMN ID of aHPLMN. In a further aspect, when the determination component 912determines that the connection to the PLMN has been established, theFDQN building component 914 can build the FQDN by retrieving a list ofPLMN-specific FQDNs. For example, the list may include a prioritizedlist of FQDNs associated with a specific PLMN, determining if thecurrent PLMN is found in the list, and attempting to build the FQDNusing each of the prioritized FQDNs in order of priority until the FQDNis built. Moreover, in another aspect, if the attempting to build theFQDN using the each of the prioritized FQDNs fails, the FDQN buildingcomponent 914 can build the FQDN using a PLMN ID of a HPLMN.Furthermore, when the determination component 912 determines that theconnection to the PLMN has not been established, the FDQN buildingcomponent 914 can build the FQDN by retrieving a list of PLMN-specificFQDNs. For example, the list may a prioritized list of FQDNs associatedwith a specific PLMN, determining if the list comprises a wildcard PLMN,and the FDQN building component 914 can build the FQDN based on thewildcard PLMN if it is determined that the list comprises the wildcardPLMN. In yet a further aspect, when the determination component 912determines that the list does not comprise the wildcard PLMN, the FDQNbuilding component 914 can build the FQDN using a PLMN ID of a HPLMN.Moreover, when the determination component 912 determines that theconnection to the PLMN has been established, the FDQN building component914 can build the FQDN by retrieving a list comprising informationrelated to a plurality of VPLMNs, the determination component candetermine if the PLMN is found in the list, and the FDQN buildingcomponent 914 can build the FQDN using a PLMN ID of the current PLMN ifit is determined that the PLMN is found in the list. In an aspect, whenthe determination component 912 determines that the PLMN is not found inthe list, the FDQN building component 914 can build the FQDN using aPLMN ID of a HPLMN. In still a further aspect, when the determinationcomponent 912 determines that the connection to the PLMN has not beenestablished, the FDQN building component 914 can build the FQDN using aPLMN ID of a HPLMN.

In yet a further aspect, the ePDG selection component 916 can select anePDG based on the FQDN built by the FQDN building component 914.

The apparatus may include additional components that perform each of theblocks of the algorithm in the aforementioned flowcharts of FIG. 9. Assuch, each block in the aforementioned flowcharts of FIG. 9 may beperformed by a component and the apparatus may include one or more ofthose components. The components may be one or more hardware componentsspecifically configured to carry out the stated processes/algorithm,implemented by a processor configured to perform the statedprocesses/algorithm, stored within a computer-readable medium forimplementation by a processor, or some combination thereof.

FIG. 10 is a diagram 1000 illustrating an example of a hardwareimplementation for an apparatus 902′ employing a processing system 1014.The processing system 1014 may be implemented with a bus architecture,represented generally by the bus 1024. The bus 1024 may include anynumber of interconnecting buses and bridges depending on the specificapplication of the processing system 1014 and the overall designconstraints. The bus 1024 links together various circuits including oneor more processors and/or hardware components, represented by theprocessor 1004, the components 904, 906, 908, 910, 912, 914, and 916 andthe computer-readable medium/memory 1006. The bus 1024 may also linkvarious other circuits such as timing sources, peripherals, voltageregulators, and power management circuits, which are well known in theart, and therefore, will not be described any further.

The processing system 1014 may be coupled to a transceiver 1010. Thetransceiver 1010 is coupled to one or more antennas 1020. Thetransceiver 1010 provides a means for communicating with various otherapparatus over a transmission medium. The transceiver 1010 receives asignal from the one or more antennas 1020, extracts information from thereceived signal, and provides the extracted information to theprocessing system 1014, specifically the reception component 904. Inaddition, the transceiver 1010 receives information from the processingsystem 1014, specifically the transmission component 910, and based onthe received information, generates a signal to be applied to the one ormore antennas 1020. The processing system 1014 includes a processor 1004coupled to a computer-readable medium/memory 1006. The processor 1004 isresponsible for general processing, including the execution of softwarestored on the computer-readable medium/memory 1006. The software, whenexecuted by the processor 1004, causes the processing system 1014 toperform the various functions described supra for any particularapparatus. The computer-readable medium/memory 1006 may also be used forstoring data that is manipulated by the processor 1004 when executingsoftware. The processing system 1014 further includes at least one ofthe components 904, 906, 908, 910, 912, 914, and 916. The components maybe software components running in the processor 1004, resident/stored inthe computer readable medium/memory 1006, one or more hardwarecomponents coupled to the processor 1004, or some combination thereof.The processing system 1014 may be a component of the UE 650 and mayinclude the memory 660 and/or at least one of the TX processor 668, theRX processor 656, and the controller/processor 659.

In one configuration, the apparatus 902/902′ for wireless communicationincludes means for means for connecting to a wireless communicationnetwork. In addition, the apparatus 902/902′ for wireless communicationincludes means for obtaining an internet protocol (IP) address from thewireless communication network. Further, the apparatus 902/902′ forwireless communication includes means for determining if a connection toa public land mobile network (PLMN) has been established. Moreover, theapparatus 902/902′ for wireless communication includes means forbuilding a fully qualified domain name (FQDN) based on thedetermination. In an aspect, when the means for determining determinesthat the connection to the PLMN has been established, the means forbuilding the FQDN is configured to retrieve a list of PLMN-specificFQDNs, wherein the list comprises a prioritized list of FQDNs eachassociated with a specific PLMN, determine if the PLMN is found in thelist, and attempt to build the FQDN using each of the prioritized FQDNsin order of priority until the FQDN is built or retrieve a listcomprising a plurality of VPLMNs when the PLMN is a VPLMN, determine ifthe PLMN is found in the list, and build the FQDN using a PLMN ID of thePLMN if it is determined that the PLMN is found in the list. In anotheraspect, when the means for determining determines that the connection tothe PLMN has not been established, the means for building the FQDN isfurther configured to retrieve the list of PLMN-specific FQDNs, whereinthe list comprises a prioritized list of FQDNs each associated with aspecific PLMN, determine if the list comprises a wildcard PLMN, andbuild the FQDN based on the wildcard PLMN if it is determined that thelist comprises the wildcard PLMN. In yet another aspect, when the meansfor determining determines that the connection to the PLMN has beenestablished and that the PLMN is not found in the list of PLMN-specificFQDNs, the means for building the FQDN is further configured to buildthe FQDN using the PLMN ID of a HPLMN. Moreover, when the means forbuilding fails to build the FQDN using each of the prioritized FQDNs,the means for building the FQDN is further configured to build the FQDNusing the PLMN ID of a HPLMN. Still further, when the means fordetermining determines that the list of PLMN-specific FQDNs does notcomprise the wildcard PLMN, the means for building the FQDN is furtherconfigured to build the FQDN using the PLMN ID of a HPLMN. Furtherstill, when the means for determining determines that the PLMN is notfound in the list comprising the plurality of VPLMNs, the means forbuilding the FQDN is further configured to build the FQDN using the PLMNID of a HPLMN. Additionally, the apparatus 902/902′ for wirelesscommunication includes means for selecting an ePDG based on the FQDN.

The aforementioned means may be one or more of the aforementionedcomponents of the apparatus 902 and/or the processing system 1014 of theapparatus 902′ configured to perform the functions recited by theaforementioned means. As described supra, the processing system 1014 mayinclude the TX Processor 668, the RX Processor 656, and thecontroller/processor 659. As such, in one configuration, theaforementioned means may be the TX Processor 668, the RX Processor 656,and the controller/processor 659 configured to perform the functionsrecited by the aforementioned means.

It is understood that the specific order or hierarchy of blocks in theprocesses/flowcharts disclosed is an illustration of exemplaryapproaches. Based upon design preferences, it is understood that thespecific order or hierarchy of blocks in the processes/flowcharts may berearranged. Further, some blocks may be combined or omitted. Theaccompanying method claims present elements of the various blocks in asample order, and are not meant to be limited to the specific order orhierarchy presented.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” The word “exemplary” is used hereinto mean “serving as an example, instance, or illustration.” Any aspectdescribed herein as “exemplary” is not necessarily to be construed aspreferred or advantageous over other aspects. Unless specifically statedotherwise, the term “some” refers to one or more. Combinations such as“at least one of A, B, or C,” “at least one of A, B, and C,” and “A, B,C, or any combination thereof” include any combination of A, B, and/orC, and may include multiples of A, multiples of B, or multiples of C.Specifically, combinations such as “at least one of A, B, or C,” “atleast one of A, B, and C,” and “A, B, C, or any combination thereof” maybe A only, B only, C only, A and B, A and C, B and C, or A and B and C,where any such combinations may contain one or more member or members ofA, B, or C. All structural and functional equivalents to the elements ofthe various aspects described throughout this disclosure that are knownor later come to be known to those of ordinary skill in the art areexpressly incorporated herein by reference and are intended to beencompassed by the claims. Moreover, nothing disclosed herein isintended to be dedicated to the public regardless of whether suchdisclosure is explicitly recited in the claims. No claim element is tobe construed as a means plus function unless the element is expresslyrecited using the phrase “means for.”

What is claimed is:
 1. A method of wireless communication, comprising:connecting to a wireless communication network; obtaining an internetprotocol (IP) address from the wireless communication network;determining if a connection to a first public land mobile network (PLMN)has been established; building a fully qualified domain name (FQDN)based on the determination; and selecting an evolved packet data gateway(ePDG) based on the FQDN; wherein a list of PLMN-specific FQDNscomprises a prioritized list of FQDNs each associated with a specificPLMN; wherein when it is determined that the connection to the firstPLMN has been established, the building the FQDN comprises: retrievingthe list of PLMN-specific FQDNs, determining if the first PLMN is foundin the list of PLMN-specific FQDNs, and attempting to build the FQDNusing each of the prioritized FQDNs in order of priority until thebuilding of the FQDN is completed; or retrieving a list comprising aplurality of visited PLMNs (VPLMNs) when the first PLMN is a VPLMN,determining if the first PLMN is found in the list comprising theVPLMNs, and building the FQDN using a PLMN identification (PLMN ID) ofthe first PLMN if it is determined that the first PLMN is found in thelist comprising the VPLMNs.
 2. The method of claim 1, wherein when it isdetermined that the connection to the first PLMN has been establishedand that the first PLMN is not found in the list of PLMN-specific FQDNs,the building the FQDN comprises: building the FQDN using the PLMN ID ofa home PLMN (HPLMN).
 3. The method of claim 1, wherein if the attemptingto build the FQDN using each of the prioritized FQDNs fails, thebuilding the FQDN further comprises: building the FQDN using the PLMN IDof a home PLMN (HPLMN).
 4. The method of claim 1, wherein when it isdetermined that the first PLMN is not found in the list comprising theplurality of VPLMNs, the building the FQDN comprises: building the FQDNusing the PLMN ID of a home PLMN (HPLMN).
 5. The method of claim 1,wherein when it is determined that the connection to the first PLMN hasnot been established, the building the FQDN further comprises:retrieving the list of PLMN-specific FQDNs, determining if the list ofPLMN-specific FQDNs comprises a wildcard PLMN, and building the FQDNbased on the wildcard PLMN if it is determined that the list ofPLMN-specific FQDNs comprises the wildcard PLMN.
 6. The method of claim5, wherein when it is determined that the list of PLMN-specific FQDNsdoes not comprise the wildcard PLMN, the building the FQDN furthercomprises: building the FQDN using the PLMN ID of a home PLMN (HPLMN)and user equipment location information.
 7. An apparatus for wirelesscommunication, comprising: means for connecting to a wirelesscommunication network; means for obtaining an internet protocol (IP)address from the wireless communication network; means for determiningif a connection to a first public land mobile network (PLMN) has beenestablished; means for building a fully qualified domain name (FQDN)based on the determination; and means for selecting an evolved packetdata gateway (ePDG) based on the FQDN; wherein a list of PLMN-specificFQDNs comprises a prioritized list of FQDNs each associated with aspecific PLMN; wherein when it is determined that the connection to thefirst PLMN has been established, the means for building the FQDN isconfigured to: retrieve the list of PLMN-specific FQDNs, determine ifthe first PLMN is found in the list of PLMN-specific FQDNs, and attemptto build the FQDN using each of the prioritized FQDNs in order ofpriority until the building of the FQDN is completed; or retrieve a listcomprising a plurality of visited PLMNs (VPLMNs) when the first PLMN isa VPLMN, determine if the first PLMN is found in the list comprising theplurality of VPLMNs, and build the FQDN using a PLMN identification(PLMN ID) of the first PLMN if it is determined that the first PLMN isfound in the list comprising the VPLMNs.
 8. The apparatus of claim 7,wherein when it is determined that the connection to the first PLMN hasbeen established and that the first PLMN is not found in the list ofPLMN-specific FQDNs, the means for building the FQDN is furtherconfigured to: build the FQDN using the PLMN ID of a home PLMN (HPLMN).9. The apparatus of claim 7, wherein if the attempting to build the FQDNusing each of the prioritized FQDNs fails, the means for building theFQDN is further configured to: build the FQDN using the PLMN ID of ahome PLMN (HPLMN).
 10. The apparatus of claim 7, wherein when it isdetermined that the first PLMN is not found in the list comprising theplurality of VPLMNs, the means for building the FQDN is furtherconfigured to: build the FQDN using the PLMN ID of a home PLMN (HPLMN).11. The apparatus of claim 7, wherein when it is determined that theconnection to the first PLMN has not been established, the means forbuilding the FQDN is further configured to: retrieve the list ofPLMN-specific FQDNs, determine if the list of PLMN-specific FQDNscomprises a wildcard PLMN, and build the FQDN based on the wildcard PLMNif it is determined that the list of PLMN-specific FQDNs comprises thewildcard PLMN.
 12. The apparatus of claim 11, wherein when it isdetermined that the list of PLMN-specific FQDNs does not comprise thewildcard PLMN, the means for building the FQDN is further configured to:build the FQDN using the PLMN ID of a home PLMN (HPLMN).
 13. Anapparatus for wireless communication, comprising: a memory; and at leastone processor coupled to the memory and configured to: connect to awireless communication network; obtain an internet protocol (IP) addressfrom the wireless communication network; determine if a connection to afirst public land mobile network (PLMN) has been established; build afully qualified domain name (FQDN) based on the determination; andselect an evolved packet data gateway (ePDG) based on the FQDN; whereina list of PLMN-specific FQDNs comprises a prioritized list of FQDNs eachassociated with a specific PLMN; wherein when it is determined that theconnection to the first PLMN has been established, the at least onprocessor is configure to build the FQDN by: retrieving the list ofPLMN-specific FQDNs, determining if the first PLMN is found in the listof PLMN-specific FQDNs, and attempting to build the FQDN using each ofthe prioritized FQDNs in order of priority until the building of theFQDN is completed; or retrieving a list comprising a plurality ofvisited PLMNs (VPLMNs) when the first PLMN is a VPLMN, determining ifthe first PLMN is found in the list comprising the VPLMNs, and buildingthe FQDN using a PLMN identification (PLMN ID) of the first PLMN if itis determined that the first PLMN is found in the list comprising theVPLMNs.
 14. The apparatus of claim 13, wherein when it is determinedthat the connection to the first PLMN has been established and that thefirst PLMN is not found in the list of PLMN-specific FQDNs, the at leastone processor is configured to build the FQDN by: building the FQDNusing the PLMN ID of a home PLMN (HPLMN).
 15. The apparatus of claim 13,wherein if the attempting to build the FQDN using each of theprioritized FQDNs fails, the at least one processor is configured tobuild the FQDN by: building the FQDN using the PLMN ID of a home PLMN(HPLMN).
 16. The apparatus of claim 13, wherein when it is determinedthat the first PLMN is not found in the list comprising the plurality ofVPLMNs, the at least one processor is configured to build the FQDN by:building the FQDN using the PLMN ID of a home PLMN (HPLMN).
 17. Theapparatus of claim 13, wherein when it is determined that the connectionto the first PLMN has not been established, the at least one processoris configured to build the FQDN by: retrieving the list of PLMN-specificFQDNs, determining if the list of PLMN-specific FQDNs comprises awildcard PLMN, and building the FQDN based on the wildcard PLMN if it isdetermined that the list of PLMN-specific FQDNs comprises the wildcardPLMN.
 18. The apparatus of claim 17, wherein when it is determined thatthe list of PLMN-specific FQDNs does not comprise the wildcard PLMN, theat least one processor is configured to build the FQDN by: building theFQDN using the PLMN ID of a home PLMN (HPLMN).
 19. A non-transitorycomputer-readable medium storing computer executable code for wirelesscommunication, comprising code for: connecting to a wirelesscommunication network; obtaining an internet protocol (IP) address fromthe wireless communication network; determining if a connection to afirst public land mobile network (PLMN) has been established; building afully qualified domain name (FQDN) based on the determination; andselecting an evolved packet data gateway (ePDG) based on the FQDN;wherein a list of PLMN-specific FQDNs comprises a prioritized list ofFQDNs each associated with a specific PLMN; wherein when it isdetermined that the connection to the first PLMN has been established,the code is configured to build the FQDN by: retrieving a list ofPLMN-specific FQDNs, determining if the first PLMN is found in the listof PLMN-specific FQDNs, and attempting to build the FQDN using each ofthe prioritized FQDNs in order of priority until the building of theFQDN is completed; or retrieving a list comprising a plurality ofvisited PLMNs (VPLMNs) when the first PLMN is a VPLMN, determining ifthe first PLMN is found in the list comprising the VPLMNs, and buildingthe FQDN using a PLMN identification (PLMN ID) of the first PLMN if itis determined that the first PLMN is found in the list comprising theVPLMNs.
 20. The non-transitory computer-readable medium of claim 19,wherein when it is determined that the connection to the first PLMN hasbeen established and that the first PLMN is not found in the list ofPLMN-specific FQDNs, the code is configured to build the FQDN by:building the FQDN using the PLMN ID of a home PLMN (HPLMN).
 21. Thenon-transitory computer-readable medium of claim 19, wherein if theattempting to build the FQDN using each of the prioritized FQDNs fails,the code is configured to build the FQDN by: building the FQDN using thePLMN ID of a home PLMN (HPLMN).
 22. The non-transitory computer-readablemedium of claim 19, wherein when it is determined that the first PLMN isnot found in the list comprising the plurality of VPLMNs, the code isconfigured to build the FQDN by building the FQDN using the PLMN ID of ahome PLMN (HPLMN).
 23. The non-transitory computer-readable medium ofclaim 19, wherein when it is determined that the connection to the firstPLMN has not been established, the code is configured to build the FQDNby: retrieving the list of PLMN-specific FQDNs, determining if the listof PLMN-specific FQDNs comprises a wildcard PLMN, and building the FQDNbased on the wildcard PLMN if it is determined that the list ofPLMN-specific FQDNs comprises the wildcard PLMN.
 24. The non-transitorycomputer-readable medium of claim 23, wherein when it is determined thatthe list of PLMN-specific FQDNs does not comprise the wildcard PLMN, thecode is configured to build the FQDN by: building the FQDN using thePLMN ID of a home PLMN (HPLMN).